L07_18_Sept_Petrology

3 k2o 004 06 4 na2o 04 2 4

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Unformatted text preview: weathered fragments (ground- up bits) of the other rock types (also including sedimentary), typically deposited by water. Also includes ‘chemical’ sediments, such as limestone, and salt deposits. Metamorphic Rocks that have been parAally altered, via parAal melAng or chemical processes (or both). The original rock type (sedimentary or igneous) can usually be inferred. Complete melAng renders the rock an ‘igneous rock’. The previous figure depicts events / phenomena happening in the crust A useful scheme for understanding igneous rocks Rock Types consAtuent minerals Rock and Mineral EvoluAon (mantle) Ocean Crust ConAnental Crust New oceanic crust can be thought of as the first and most primiAve rocks derived from the mantle molten silicate solid silicate Oxide Mantle Basalt Granite SiO2 46 % 48 % 72 % MgO 38 % 10 % 1 % Al2O3 4 % 13 % 14 % CaO 3 % 10 % 2 % FeO, Fe2O3 8 % 11 % 3 % K2O 0.04 % 0.6 % 4 % Na2O 0.4 % 2 % 4 % Virtually all rock types are ulAmately derived from mantle rocks. But most rocks are chemically very different from mantle rocks. How can we...
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This document was uploaded on 03/26/2014 for the course GEC AS.270.103 at Johns Hopkins.

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